JPH0473090A - Cloth feeding mechanism for sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a cloth feeding mechanism of a sewing machine, and more specifically, a cloth feeding motor that is different from the drive motor that drives the main shaft moves the workpiece cloth forward and backward. This invention relates to a fabric feeding mechanism of a sewing machine that moves the fabric backward.

[Prior Art] Conventionally, a cloth feeding mechanism has been known in which a cloth feeding motor provided separately from a main shaft drive motor is driven to transport a workpiece cloth forward and backward. This mechanism includes a back-and-forth drive mechanism that moves a feed table on which feed teeth are formed for transferring the work cloth in the front-rear direction, and a vertical drive mechanism that moves the feed table in the up-down direction. As shown in Figure 4 (schematic side view of the inside of the sewing machine bed), the front and rear drive mechanism consists of a fabric feed motor (pulse motor) P that rotates forward and backward at a predetermined angle.
and a driven gear P3 that meshes with the drive gear P2 of the cloth feed motor P1, and a swinging arm P5 that can swing in the direction of arrow a about a support shaft P4, and a swinging arm P5 provided on the free end side of the swinging arm P5. The horizontal feeding arm P8 is rotatably supported on the connecting shaft P6 and slidably supported on the free end side of the horizontal supporting surface P7. A guide shaft P9 is vertically provided on both the upper and lower surfaces of the horizontal feed arm P8, and the guide shaft P9 is the feed base P]
0 (feed dog P]] is formed at the upper part) so that it can move up and down. Therefore, when the swing arm P5 swings around the support shaft P4 due to the forward and reverse rotation of the cloth feed motor P1 at a predetermined angle, the horizontal feed arm P8 supported by the connecting shaft P6 moves in the direction indicated by the arrow (back and forth). However, the feed table PIO is driven in the front-back direction via the guide shaft P9.

On the other hand, the vertical drive mechanism rotates an eccentric cam P12 that rotates in synchronization with the main shaft (not shown) to move the arrow C to the feed table PIO.
The feed table PIO is moved up and down along the guide axis P9 by applying a movement in the direction.

The workpiece cloth is transferred by applying a combination of such vertical and one-frontal movements to the feed table P]O.

[Problems to be Solved by the Invention] In this type of cloth feeding mechanism, in order to make feeding advantageous at the edge of the cloth and during step sewing, forward feeding and backward feeding (back feeding) are performed to move the feed dog P9 forward and backward. The moving position may change. That is, in forward feed, the feed dog P9 is moved away from the most forward end (toward the operator's side) of the square hole in the throat plate (not shown), and in reverse feed, the feed dog P9 is moved from the rearmost end (toward the operator's side) to the near side. P9 protrudes from the square hole and connects each cloth feed motor P.
Move it to a position determined according to the rotation angle of step 1.

In the conventional mechanism described above, when attempting to perform such feeding, there is a problem in that a difference occurs in the amount of feed between forward feed and backward feed, as shown below.

That is, as shown in FIG. 5, in the conventional mechanism, the horizontal feed arm P8 is supported at two locations: the connecting shaft P6, which swings about the support shaft P4, and the horizontal support surface P7.
Due to the rocking, the horizontal feed arm P8 is tilted, and the guide shaft P9 is tilted with respect to the position on the vertical line (indicated by a solid line). The feed table P10 moves up and down along the second guide axis P9, so it moves on the trajectory K during forward feeding, and moves on the trajectory K during backward feeding.As a result, the cloth feed motor P] Even if the reciprocating rotation angles θ are the same, a problem arises in that there is a difference between the cloth feed amount d1 during forward feed and the cloth feed amount d2 during backward feed.

If there is a difference in the amount of feed between the forward feed and the backward feed, the pattern shape will be distorted and the desired pattern cannot be sewn, especially when sewing large patterns that require a large number of counts.

The cloth feed mechanism of the sewing machine of the present invention solves the above problems and aims to reduce the difference in "forward feed" and "reverse feed".

Structure of the Invention [Means for Solving the Problems] The cloth feed mechanism of the sewing machine of the present invention (in synchronization with the rotation of the main shaft of the sewing machine, a cloth feed motor different from the drive motor that drives the main shaft) moves the work cloth forward. and a cloth feeding mechanism for a sewing machine that moves the cloth rearward, comprising: a swing arm that swings about a predetermined support shaft by the rotation of the cloth feed motor, and a swing arm that has a connecting shaft on its free end side; a horizontal feed arm rotatably supported by a connecting shaft of the movable arm and formed with a supported portion extending from the supported position; and a horizontal feed arm provided opposite to the supported portion of the horizontal feed arm. a feed arm support portion that supports the supported portion so as to be slidable in the front-rear direction; and a feed stand that is supported by the horizontal feed arm so as to be movable up and down and is provided with feed teeth for transferring the work cloth. , a feeder vertical drive mechanism for moving the feeder vertically in synchronization with the rotation of the main shaft of the sewing machine; The gist is that it is formed in a circular arc shape with a radius of curvature corresponding to the distance between the center axes of.

[Function] In the cloth feeding mechanism of the sewing machine of the present invention having the above configuration, the swinging arm swings around the support shaft by the rotation of the cloth feed motor, and the connecting shaft is moved along an arcuate trajectory around the support shaft. Draw it and make it reciprocate in the front and back direction.

The horizontal feed arm is rotatably supported by the connecting shaft, and the supported portion extending from the supporting position is slidably supported by the feeding arm support portion, so that the horizontal feed arm is rotatably supported by the connecting shaft. Then, the supported part is moved while sliding on the surface of the sending arm support part. The surface shape of the feeding arm support portion in the front-rear direction is formed into an arc shape with a radius of curvature corresponding to the distance between the center axes of the support shaft and the connecting shaft. Therefore, the movement of the supported part of the horizontal feed arm corresponds to the movement of the connecting shaft,
The horizontal feed arm supported by the connecting shaft and the feed arm support section moves approximately in parallel.

The feed table on which the feed teeth are formed is supported by the horizontal feed arm so as to be movable up and down, and is moved up and down by the feed table up-and-down drive mechanism, and also moves back and forth by transmitting the longitudinal movement of the horizontal feed arm. Therefore, due to the substantially parallel movement of the horizontal feed arm, the vertical movement locus of the feed table will not be inclined regardless of the position of the connecting shaft.

As a result, the difference in feed amount between forward feed and backward feed is reduced.

[Embodiment] An embodiment of the cloth feeding mechanism of the sewing machine of the present invention will be described below.

As shown in the perspective view of FIG. 1, the cloth feeding mechanism of the sewing machine of the embodiment includes a back and forth drive mechanism 1 that moves a feed table to which a feed dog H is fixed in the front and rear directions, and a back and forth drive mechanism 1 that moves the feed table in the vertical direction. It is provided with a vertical drive mechanism 3 that moves. It also includes an electronic control device 5 shown in the block diagram of FIG.

As shown in Fig. 1, the longitudinal drive mechanism includes a pulse motor], a swinging lever] 3, a support shaft] 5, a swinging arm] 7, a connecting shaft] 9, a horizontal feed arm 2), and a feed arm support. It consists of part 23, etc. In addition, in the figure, the rotary hook K is shown by a dashed-dotted line in order to facilitate understanding of the arrangement of these components.

The pulse motor 11 is independent from the drive system of the lower shaft S (that is, the drive system of the main shaft) that is linked to the vertical movement of the sewing machine needle.
The drive is controlled in synchronization with the lower shaft S by an electronic control device 5 (FIG. 2), which will be described later. Drive gear IIA is on the pressure shaft.
is fixed. A light shielding plate 11B is attached to drive gear IIA. Further, the photointerrupter 25 is connected to the light shielding plate 11.
It is installed at the position where B passes.

Swing lever] 3 is a plate material having two levers bent in an abbreviated shape. A support shaft 15 is inserted through the bent portion, and the swinging lever 3 is swingably supported by the support shaft 15. A driven gear 13 that meshes with the drive gear IIA is attached to the tip of the lever that extends toward the front (diagonally to the right in the drawing).
A is attached. The center of the pitch circle of the driven gear 13A coincides with the axis of the support shaft]5. In the embodiment, the driven gear 13A is made of a resin product and is assembled so as to tightly mesh with the drive gear 11A. Due to this tight assembly, the teeth of the driven gear 13A are plastically deformed to match the shape of the teeth of the drive gear 1]A. As a result, a gear transmission mechanism with extremely low backlash is realized.

On the other hand, the side surface of the swinging arm 7 is fixed to the lever extending upward from the bent portion.

The swing arm 17 is a substantially H-shaped member. A bearing portion 17A is formed at each of the lower portions of the vertical shaft on both sides thereof, and the support shaft 15 is inserted therethrough. The swing arm 17 is thus swingably supported by the support shaft 5 integrally with the swing lever 13. Note that the support shaft 5 is suspended at both ends by shaft supports 15A and 15B with a slight gap above a base (not shown).

Bearing portions 1 are mounted on each of the upper portions of the vertical shaft on both sides of the swing arm] 7.
7B is formed. Between each bearing part 17B, a connecting shaft 1
9 is handed over.

The horizontal feed arm 21 supported by the connection shaft 19 is a thick plate having a substantially triangular shape. A roller 21A (supported part) is provided on the side surface of the front end corresponding to the apex of the triangle. Bearings 21B and 21C are provided on both sides of the rear end corresponding to the base of the triangle. The connecting shaft 19 passes through the bearing portion 21B. A penetrating connecting shaft] 9 is inserted halfway into the bearing portion 21C.

In this way, the horizontal feed arm 21 is rotatably supported by the connection shaft 19.

Further, a tension spring 27 is tensioned between the side surface of the horizontal feed arm 21 and the lower frame F. The tension spring 27 biases the horizontal feed arm 2 downward, so that the roller 21A
is always kept in close contact with the surface 23A of the feed arm support section 23, which will be described later.

Further, a guide rod 29 is fixed to the rear bearing portion 21C in a state that it passes through the bearing portion 21C. The axis of the guide rod 29,
It intersects perpendicularly with the plate surface of the horizontal feed arm 2]. The upper part of the guide rod 29 penetrates the feed bar body,
The portion that protrudes from the lower part penetrates the guide portion D1 extending below the feed bar. That is, the feed base is the guide rod 29
is supported so as to be movable in the vertical direction on the plate surface of the horizontal feed arm 2].

The feed arm support portion 23 is screwed to the frame F. The surface 23A on which the roller 21A slides has an arcuate shape in the front-rear direction. The above-mentioned horizontal feed arm 21 is rotatably supported by the connecting shaft] 9, and this surface 23
The rack is slidably supported by A. The rack is passed horizontally according to the principle described later.

The explanatory diagram of FIG. 3 shows this surface 23A in cross section.

In the embodiment, the sum of the radius of curvature of the surface 23A and the radius of the roller 21A is designed to be the same as the distance between the centers of the support shaft 5 and the connecting shaft 19.

The operation of the above-mentioned longitudinal drive mechanism 1 will be briefly explained.

As shown in FIG. 1, when the pulse motor]] rotates in forward and reverse directions and its driving gear []]A sends the driven gear 13A in the vertical direction, the swinging lever 13 moves the support shaft [5]. Swings to the center. Then, the swinging arm ]7, which swings and is integrally fixed to the bar 13, similarly swings about the support shaft]5. Due to the swinging of this swinging arm]7, the connecting shaft]9 reciprocates in the front and back direction. A frame is passed between the connecting shaft] 9 and the feeding arm support part 23, and the horizontal feeding arm 2] reciprocates in the front and rear direction in alignment with the connecting shaft 9. Regarding the behavior of this horizontal feeding arm 2, , will be explained in detail later.Then, the rear guide rod 2
9, the feed bar is pulled in the front-rear direction, and the feed dog H is moved in the front-rear direction.

Next, the vertical drive mechanism 3 will be explained.

As shown in FIG. 1, the vertical drive mechanism 3 includes a lower shaft S, an eccentric cam 31, a vertical lever 33, and the like.

The timing belt is attached to the pulley S on the lower shaft S,
It is rotated in synchronization with a main shaft (not shown) that moves the sewing machine needle up and down.

The eccentric cam 31 is a cam that is eccentrically provided on the lower shaft S. The amount of eccentricity is determined according to the vertical stroke of the feed dog H.

The vertically movable lever 33 (the upper front end is swingably supported by the rod 33A, and the lower surface of the abdomen hits the eccentric cam 3)↑
concubine

A roller 35 is rotatably supported on the side surface of the rear end of the vertically movable lever 33. A support surface 37 provided on the lower surface of the feed platform is in sliding contact with the roller 35. A front compression spring 39 is disposed between the guide portion D of the feed bar and the horizontal feed arm 21, and the feed bar is biased downward. With the above configuration, the support surface 37 is always in close contact with the roller 35, and the vertically moving lever 33 is always in close contact with the eccentric cam 3. Therefore, the roller 35 moves up and down accurately in accordance with the shape of the eccentric cam 3, and the feed platform is also accurately moved. It moves up and down according to the .

Next, regarding the electronic control device 5 that controls the above-mentioned mechanism,
This will be explained based on FIG. Electronic control unit 5 (Table well-known C
PU51. ROM53. It is an arithmetic and logic operation circuit that includes a RAM 55, input/output interfaces 57, 59, and the like. The input interface 57 includes an operation switch 6 for power supply, etc.]
and a photointerrupter 25 are connected. A drive circuit 65 of a main shaft motor 63 that rotates the lower shaft S via a timing belt is connected to the output interface 59. A drive circuit 67 of a pulse motor 1 of a longitudinal drive mechanism is also connected to the output interface 59.
is connected.

The cloth feeding device of the sewing machine described above operates as follows. When the power is turned on, the electronic control unit 5 uses the on/off signal of the photointerrupter 25 to determine the origin of the phase of the drive gear IIA of the pulse motor 1. That is,
In the example shown in FIG. 1, the engagement between the drive gear A and the driven gear 13A is located at the center of the driven gear 13A.

When determining the phase origin, this engagement is moved to the upper end M of the area indicated by the arrow M (the engagement area for forward feed) using the signal from the photointerrupter 25. At the origin, (front swing arm) 7 is tilted most forward, the connecting shaft 19 is moved most forward, and the feed dog H is at the most forward end of the square hole (not shown) (towards the operator)
will be placed in

Thereafter, sewing is performed by a known method in accordance with the operation of the operation switch. For example, feed pitch data indicating the amount of work cloth to be transferred (feed pitch) for each stitch is read from the sewing data of a predetermined pattern. Then, the pulse motor rotates in synchronization with the rotation of the lower shaft S by a rotation angle determined from this feed pitch data, that is, a rotation angle corresponding to obtaining the feed pitch specified by the data.

At this time, even if the feed pitch data indicates forward feed (the melon drive gear IIA is rotated from the upper end M1 of the engagement area indicated by the arrow M as described above), the driven gear 13A is rotated upward by an amount corresponding to the rotation angle. The swinging lever] 3 is then rotated upward.Then, the swinging lever 3 is moved upward in synchronization with the timing of the rotation of the lower shaft S.

As a result of these rotations and back movements being repeated, the connecting shaft]9.
Via the horizontal feed arm 21 and the like, the feed dog H reciprocates in the front and rear directions at the front part of a square hole (not shown). This reciprocating movement in the front and back direction is combined with the vertical movement by the vertical drive mechanism 3, and the feed dog H moves in a trajectory shown by the arrow K]. This movement is performed at the front part of the square hole (not shown), so in forward feeding, when feeding the work cloth, the feed dog H is attached to the edge of the cloth at the start of sewing.
Most of them bite, which is advantageous for feeding.

On the other hand, if the feed pitch data is backward feed data,
By the rotation of the work cloth pulse motor 1, the drive gear II
A and the driven gear 13A are engaged in the area indicated by the arrow U (
The pulse motor 1]A is controlled so that the feed dog H is located at the rearmost end (farthest from the operator) of a square hole (not shown). do. Then, similarly to the forward feed, the drive gear 11A is rotated from the lower end U of the meshing region indicated by the arrow U to a predetermined rotation angle (
The drive gear IIA of the pulse motor 11 sends the driven gear 13A downward by the rotation angle determined from the feed pitch data, and rotates the swing lever 3 downward. Later, it makes a return movement in accordance with the timing of the rotation of the lower shaft S.

As a result of such rotation and back movement, the connecting shaft]9. Horizontal feed @2
A feed dog H reciprocates in the front and back direction through the first and second parts at the rear of a square hole (not shown). This back and forth reciprocating motion,
The vertical movement by the vertical drive mechanism 3 is combined to cause the feed dog HIL to move in a trajectory shown by the arrow 2. This movement is performed at the rear of the square hole (not shown), so when feeding the workpiece cloth from far away to the operator in the backward feed, most of the feed dog H engages with the edge of the cloth at the start of sewing.
It is advantageous for sending.

As described above, the feed dog H is aligned with the arrow K] and the arrow 2.
The behavior of the horizontal feed arm 2 when it moves in the direction is shown in the explanatory diagram of the above mechanism seen from the side in FIG.

When the swinging arm [7] swings around the support shaft 15 due to the above-described operation, the connecting shaft [9] draws an arcuate trajectory centering on the support shaft [5] and reciprocates in the front-back direction. In the figure, the swing region during forward feeding is in the first quadrant. The locus of movement of the feed dog H during forward feeding is indicated by the reference numeral 1, as in FIG. The swing region during backward feeding is in the second quadrant. The movement locus of the feed dog H during backward feeding is indicated by the symbol 2 as in Fig. 1.
Indicated by

As can be understood from the figure, the reciprocating motion of the connecting shaft] 9 in the front-rear direction (horizontal direction in the drawing) is an arc-shaped motion centered on the support shaft] 5, whether it is forward feeding or backward feeding. Since it draws a trajectory, its back-and-forth reciprocating motion includes a vertical motion component. With the above configuration (the surface 23 of the horizontal feed arm support part 23
A(t,, as described above, is formed in an arc shape with a predetermined radius of curvature. Therefore, as the connecting shaft] 9 moves, the roller 21A of the horizontal feed arm 21 moves along this surface 2.
When the roller 2]A reciprocates in the front-rear direction at 3At, the roller 2]A moves up and down in accordance with the up-and-down movement of the connecting shaft 19. As a result, the horizontal feed arm 21 reciprocates back and forth while maintaining its horizontal position.

In other words, the guide rod 29 is
moves vertically. Therefore, for example, if the swing angle θ of the swinging arm 17 is the same for forward feeding and backward feeding,
The forward feed amount d1 and the backward feed id2 become the same.

In other words, if the pulse motor 1 is controlled to rotate by the rotation angle determined from the feed pitch data, the feed pitch of the feed dog H can be obtained in accordance with the rotation angle, whether forward or backward.

As explained above, according to the fabric feeding mechanism of the sewing machine of the embodiment, the surface shape of the surface 23A of the feeding arm support portion 23 in the front-rear direction corresponds to the center-to-center distance between the support shaft 15 and the connecting shaft ]9. Since the guide rod of the horizontal feed arm 21 is formed into an arc shape with a radius of curvature, the guide rod of the horizontal feed arm 21 moves in parallel while remaining vertical, and the feed platform is not tilted regardless of the position of the connecting shaft 19. As a result, theoretically, the forward feed and backward feed have the same amount of feed, and the difference between the two feeds is extremely reduced, which is an excellent effect.

Therefore, even if the forward feed and backward feed move the feed dog H, which is advantageous for feeding the work cloth as described above, the difference in the feed amount between forward feed and backward feed is extremely small, so it cannot be counted. Large patterns with many patterns can be sewn neatly as designed. By feeding the work cloth as described above, unlike the conventional mechanism, there is no difference in the feeding amount and the pattern is not distorted.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. For example, in the embodiment, the roller 21 is used as the supported part of the horizontally moving arm, but a contact with a sharp lower end may also be used. When using this contact,
The radius of curvature of the surface 23A of the feeding arm support portion 23 is
and the connecting shaft 19.

Effects of the Invention As detailed above, according to the cloth feeding mechanism of the sewing machine of the present invention, the surface shape of the feeding arm support portion in the front and back direction has a radius of curvature corresponding to the center-to-center distance between the support shaft and the connecting shaft. Since it is formed into a circular arc shape, the horizontal feed arm moves substantially in parallel, and the feed table is hardly tilted regardless of the position of the connecting shaft. As a result, an excellent effect is achieved in that the difference in the amount of feed between forward feed and backward feed is reduced.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the fabric feeding mechanism of the sewing machine of the present invention. Fig. 2 is a block diagram of its electronic control device, Fig. 3 is an explanatory diagram explaining its operation, and Fig. 4 is a conventional mechanism. FIG. 5 is an explanatory diagram illustrating the operation of the conventional mechanism. 5... Electronic control device 3... Rocking lever 7... Rocking axis]... Horizontal feed arm 3... Feeding arm support part D... Feeding base S... Lower shaft

Claims (1)

[Scope of Claims] 1. A cloth feeding mechanism for a sewing machine that transports workpiece cloth forward and backward in synchronization with the rotation of a sewing machine main shaft by a cloth feeding motor that is different from a drive motor that drives the main shaft, comprising: A swing arm is oscillated about a predetermined support shaft by the rotation of the cloth feed motor, and has a connection shaft on its free end side, and is rotatably supported by the connection shaft of the swing arm. A horizontal feed arm having a supported portion extending from a supported position, and a feed provided opposite to the supported portion of the horizontal feed arm and supporting the supported portion slidably in the front and back direction. an arm support section; a feed base that is supported by the horizontal feed arm so as to be movable up and down and is provided with feed teeth for transferring the work cloth; and a vertical drive mechanism for moving the feed arm in the forward and backward directions, and the surface shape of the feed arm support section in the front and back direction is formed into an arc shape with a radius of curvature corresponding to the distance between the center axes of the support shaft and the connection shaft. The fabric feed mechanism of a sewing machine is characterized by: